Remove RWX PVC reference from amp-s3.yml template

It has been detected an unneeded dependence of an RWX PVC in the amp-s3.yml which can lead the deployment of AMP on OSD.

To correct this we need to remove the bellow dependency from the template:

• https://github.com/3scale/3scale-amp-openshift-templates/blob/master/amp/amp-s3.yml#L210-L219